JPS6024553B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a high frequency heating device equipped with a microprocessor;
This is related to a so-called microwave oven.

Recently, microprocessors have begun to be introduced to control microwave ovens.

Currently, a microprocessor is used to control whether the magnetron oscillates or stops.
There are various types of input information (signals) to the microprocessor for this purpose. Among them, we focus on information on whether the microwave oven door is open or closed, and the number of cycles of the commercial AC power supply. The magnetron must stop oscillating when the microwave door is opened.

Therefore, the information that the door has been opened must be input to the microprocessor, but conventionally, as shown in Figure 3, the microprocessor has one output terminal (tentatively named R10) and one input terminal. (Let's call it K) was connected by a switch that moved the opening and closing of the door. There is one problem here. Most current microprocessors have 1 MOS. Therefore, as is well known, the input impedance is high, almost no input current flows, and the operating voltage is as low as 15V at most. Therefore, if an oxide film or the like is formed on the contacts of the door switch shown in FIG. 3 and the saddle resistance increases, this film cannot be destroyed and the door switch no longer functions as a switch.

Switches with gold contacts and other special switches were used to prevent oxidation. Furthermore, in order to control the cooking time, it is necessary to count the number of cycles of the commercial AC power supply, which requires a waveform shaping circuit that converts the AC sine wave into a rectangular wave.

Therefore, the present invention aims to have a simple configuration, omit the above-mentioned special switch, and also simplify the waveform shaping circuit.One embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a circuit diagram of a microwave oven, with a fuse 3, a main switch 4,
A latch switch (first door switch) 5, a second door switch 6, and a thermoswitch 7 are connected in series.

Further, an oven lamp 8, a fan motor 9, and a neon lamp 10 are connected in parallel. Further, a thermal fuse 11 and a relay contact 12 are connected in series with the fan motor 9. This IJ Ray 12 is controlled by a microprocessor,
Resistors 13 and 14 are connected in series with the neon lamp 10 on both sides of the neon lamp. A magnetron 15 is connected to the secondary side of the high voltage transformer, a phase advance capacitor 16 is connected in series with the magnetron, and a diode 17 and a varistor 18 are connected in parallel. A high voltage reed relay 19 is provided in series with the diode 17 and is controlled by a microprocessor. Further, the power supply circuit 21 of the control circuit 20 is connected after the main switch 4. FIG. 2 shows a part of the control circuit 20 of FIG. 1, and the microprocessor 22 is a PM
It is an OS LSI with four input terminals (K., K2, K.
4, named K8).

One of the terminals & is connected to the emitter of the phototransistor 23 and grounded via the resistor 24. The collector of the phototransistor 23 is connected to a DC positive power supply. Note that the power supply circuit 21 and the control circuit 20 are not directly related to the present invention and are well known, so they are omitted and shown only in FIG. 2. With the above configuration, the door switch can be omitted. That is, when the outlet 1 is connected to the commercial AC power source and the main switch 4 is turned on, the control circuit 20 starts operating.

If the door is closed at this time, the latch switch 5 is closed and the neon lamp 10 is turned on. The neon lamp 10 blinks according to the power waveform, so the commercial power supply is 60H.
If it is Z, it will flash 120 times per second, and if it is 50Hz, it will flash 10M groups. Since the phototransistor 23 is disposed opposite the neon lamp 10, it repeats conduction and non-conduction in response to the blinking of the neon lamp 10, and therefore 120 phototransistors (120 (
Input a pulse of 60HZ) or ION fixed (50HZ). Next, when the door is opened, the latch switch 5 is also opened, and the neon lamp 10 is not lit. Therefore, no pulse is input to the & terminal. In other words, when the door is closed, a fixed number of pulses are input, and when the door is opened, no pulses are input. This allows you to know whether the door is open or closed, and since the number of pulses twice the power supply frequency is input, it can also be used for time control. Note that you can use crab lights or LEDs instead of neon lamps,
Incandescent light bulbs cannot be used because they emit light continuously even when turned on with alternating current.

Further, in the case of an LED, a rectifying diode that can directly rectify the commercial power supply without stepping down the voltage with a transformer is required, and the number of input pulses is the same as the power supply frequency. As described above, the present invention eliminates the need for a switch for receiving door opening/closing information and also eliminates the need for a waveform shaping circuit, making it an extremely useful invention in terms of resource saving.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a high-frequency heating device showing an embodiment of the present invention, FIG. 2 is a diagram showing main parts of the control circuit in FIG. 1, and FIG. 3 is a conventional example corresponding to FIG. 2. It is a diagram. 5...Lasic switch (first door switch), 10...
Neon lamp, 23...Phototransistor, 22...
Microprocessor, 24...Resistor. Figure 2 Figure 3 Figure 1

Claims (1)

[Claims] 1. In a high-frequency heating device using a microprocessor for control, a door switch is installed to open and close the main current,
A discharge light-emitting element such as a neon tube that emits light in response to the pulsating current of the power supply is connected to the side of the door switch that is energized when the door is closed, and a phototransistor is provided opposite to this light-emitting element. A high-frequency heating device configured to combine the output of a microprocessor with the input of a microprocessor.